The present invention relates to a data processing system employing a microprocessor and more particularly to a data processing system capable of exchanging into other equivalent elements the individual integrated circuit elements within the data processing system which includes a microprocessor, without changing a control program.
In recent years, many control apparatuses using a data processing system which includes a microprocessor have been used in a variety of fields. In these types of control apparatuses, besides a microprocessor, a read-only memory (ROM), a random access memory (RAM), analog/digital (A/D) converter, digital/analog (D/A) converter, parallel-interface adapter (PIA) and the like are used in the form of integrated circuit devices which are functional devices with each one fulfilling its required function.
In a control system employing a microprocessor, there are provided numerous devices of a wide variety for each device used in the control system. However, when a device is to be replaced, the replacement device must have identical specifications as well as identical pin assignments. If a device is replaced with another that is not completely identical thereto, it may become necessary to change the control program, which is economically onerous and inconvenient.